This invention relates to welding covers to containers for electrical devices and more particularly, to a metal welding gasket used between the cover and the container of an electrical apparatus to prevent expulsion of the weld material into the container.
In electrical apparatus such as for example, distribution transformers the coil and core members are usually enclosed in a fluid-filled container. The fluid acts as part of the insulation system and it is desirable to seal the container to prevent contamination of the fluid. In the manufacture of such electrical apparatus the various bushings and the like are fixed to the container, the core and coil unit mounted therein, the necessary connections made between the core and coil unit and the bushings, the fluid introduced into the container and finally, the cover secured to the container. Often, to provide a sealed unit, the cover is welded in place to the top of the container.
In welding the cover a problem arises in that some of the welding material may be expelled during the welding into the container. As can be well understood, this can contaminate the insulating fluid, could cause a shorting in the core and coil unit, thus leading to the failure of the transformer or other electrical apparatus. Presently, to prevent this expulsion, gaskets of asbestos and glass tape are used, usually cemented to the cover or to the container. The use of asbestos and glass tape presents problems in properly aligning it around the cover or the container. Further, while the cement is hardening, care must be used in handling the cover or the container to prevent displacement of the gasket. Also, often the cement or part of the tape intrudes into the weld area, leading to poor quality welds.
It has recently been discovered that these problems can be eliminated by the use of a metal gasket which may be spot welded in position on either the cover or the container.
It is therefore, one object of this invention to provide a metal welding gasket for electrical apparatus.
It is a further object of this invention to provide a metal gasket which may be spot welded to either the cover or the container of an electrical apparatus.